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Opening membrane pores
Patents
Patents This is a list of r e c e n t l y p u b l i s h e d p a t e n t s covering d e s i g n s a n d i n v e n t i o n s of r e l e v a n c e to s y n t h e t i c m e m b r a n e technology. Where the s a m e device h a s b e e n p a t e n t e d in several c o u n t r i e s , we n o r m a l l y give t h e British p a t e n t n u m b e r . If t h e r e is no UK p a t e n t , we give the n u m b e r of a n E n g l i s h - l a n g u a g e p a t e n t , i f one exists. The p a t e n t s list is c o m p i l e d from i n t e r n a t i o n a l s o u r c e s by BHR G r o u p ' s i n f o r m a t i o n service. The facility c a n also be u s e d to carry out retrospective patent s e a r c h e s - - to t e s t t h e validity, novelty or i n f r i n g e m e n t of existing p a t e n t s or n e w ideas. BHR Group, Cranfleld, Bedford MK43 OAJ, UK, will provide free e s t i m a t e s on r e q u e s t . C o u n t r i e s c a n be identified b y the code in front of the n u m b e r a s follows:
15th a n d E a s t Streets, NW Washington, DC 20231, USA The J a p a n e s e P a t e n t Office 4-3 K a k s u m i g a s e k l 3 - c h o m e C h i y o d a - k u , Tokyo 100, J a p a n
Modifying hollow fibre membranes
G a s p l a s m a t r e a t m e n t to modify the p r o p e r t i e s of m e m b r a n e s is u s u a l l y a p p l i e d to fiat m e m b r a n e s . This invention p e r m i t s hollow fibres to be modified easily a n d with c o n s i s t e n t r e s u l t s a r o u n d the c i r c u m f e r e n c e of the fibre lumen. A b u n c h of fibres, in its h o u s i n g a n d with the e n d s s e c u r e d in the t u b e - p l a t e s , is p l a c e d in a t u b u l a r reactor. The fibres a r e filled with a s u i t a b l e g a s a n d the p r e s s u r e i n s i d e the r e a c t o r is r e d u c e d so t h a t there is a p r e s s u r e difference a c r o s s the AU A u s t r a l i a AT A u s t r i a fibres. BR Brazil BE Belgium An a n t e n n a in the s h a p e of a DD E a s t G e r m a n y CH S w i t z e r l a n d coil with d i a m e t e r larger t h a n the DK D e n m a r k DE West G e r m a n y r e a c t o r is energized a n d p a s s e s EP E u r o p e a n P a t e n t s ES S p a i n along the length of the reactor. In FI F i n l a n d FR F r a n c e GB Britain HU H u n g a r y this w a y the p l a s m a t r e a t m e n t is IR Eire IL Israel equalized t h r o u g h o u t the fibre IT Italy JP Japan b u n d l e . The p r o c e s s is rapid. KP North Korea LI L i e c h t e n s t e i n The c h o s e n m e m b r a n e is NL N e t h e r l a n d s LU L u x e m b o u r g poly(4-methylpentene) a n d the NO Norway RO R o m a n i a g a s is c a r b o n tetrafluoride. US United S t a t e s SE S w e d e n SU Soviet Union WO World P a t e n t Patent number: JP 5317661 (Patent T r e a t y Date: 3 December 1993 Cooperation Inventor: T. A n a z a w a publication) Applicant: D a i n i p p o n I n k a n d Chemical Co. BHR G r o u p does n o t o p e r a t e a d o c u m e n t delivery service for p a t e n t s , b u t full copies of the original p a t e n t d o c u m e n t s c a n be o b t a i n e d from t h e foUowing addresses: The British L i b r a r y P a t e n t E x p r e s s 25 S o u t h a m p t o n B u i l d i n g s London WC2A lAW, UK Fax: 071 323 7230 (The British L i b r a r y will a l s o s u p p l y a llst of UK l i b r a r i e s i n c l u d e d in the P a t e n t I n f o r m a t i o n Network.) US P a t e n t Office Scientific L i b r a r y
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Photographic membrane formation
The top s u r f a c e of t h i s m u l t i l a y e r m e m b r a n e is p r o d u c e d u s i n g a m a s k and a photosensitive lacquer, which forms a t h i n layer on top of a s p u t t e r e d or c h e m i c a l l y d e p o s i t e d inorganic m e m b r a n e . Both are s u p p o r t e d by a m a c r o p o r o u s m a t e r i a l s u c h as alpha-alumina.
The s p u t t e r e d m e m b r a n e is a c e r a m i c s u c h a s silica, silicon nitride, silicon carbide, or ztrconia. Metals c a n also be used: a m o n g those listed are t i t a n i u m , gold, c h r o m i u m a n d a l u m i n i u m . The s p u t t e r i n g p r o c e s s leaves a m e m b r a n e layer with pore sizes in the r a n g e 0.01-10 microns, a n d a typical t h i c k n e s s of 2-5 microns. A p h o t o s e n s i t i v e l a c q u e r is t h e n c o a t e d onto the s u r f a c e of the s p u t t e r e d m e m b r a n e a n d a m a s k with r e g u l a r l y - s p a c e d holes is u s e d to cover the surface. The d i a m e t e r of the holes is 3 microns. The l a c q u e r is developed a n d the e x p o s e d m a t e r i a l is r e m o v e d u s i n g standard lithographic methods. Next the holes in the l a c q u e r a r e d e e p e n e d b y e t c h i n g with t e t r a m e t h y l a m m o n i u m hydride, a n d finally the l a c q u e r is removed to leave a n inorganic m e m b r a n e with a regular, defined pore s t r u c t u r e at its o u t e r surface.
Patent number: WO 9323154 Date: 25 November 1993 Inventor and applicant: C.J.M. v a n RiJn
Opening membrane pores In t h i s p r o c e s s a m e m b r a n e which w a s originally s u i t a b l e for reverse o s m o s i s a p p l i c a t i o n s c a n be modified so t h a t it c a n t h e n i n s t e a d be u s e d for nanoflltration. The i n c r e a s e in pore size n e c e s s a r y to do this is o b t a i n e d by c o n t a c t i n g the m e m b r a n e (an a s y m m e t r i c hollow fibre p o l y a m i d e material) with a solution of a t r a n s i t i o n m e t a l salt, typically m a n g a n e s e . The t r a n s i t i o n m e t a l is in a low o x i d a t i o n state. The wet m e m b r a n e is t h e n w a s h e d with a s o l u t i o n of s o d i u m or p o t a s s i u m p e r m a n g a n a t e . The t r a n s i t i o n m e t a l is oxidized by t h e p e r m a n g a n a t e a n d p r e c i p i t a t e s in the p o r e s a s a m e t a l oxide, e.g. m a n g a n e s e dioxide. In the final s t e p t h e m e t a l oxide is dissolved b y r e a c t i o n with
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Patents a solution containing sodium nitrite, p o t a s s i u m iodide, s o d i u m bisulphite and hydrogen peroxide. The s e q u e n c e of s t e p s c a n be r e p e a t e d several t i m e s until the average p o r e size h a s b e e n e ~ l a r g e d to t h e d e s i r e d extent. The p r o c e s s h a s b e e n u s e d to produce nanoflltration m e m b r a n e s which will p a s s s o d i u m chloride a n d s o d i u m s u l p h a t e , w h i c h is a p r o p e r t y useful in the s e p a r a t i o n of a dye from a s o d i u m s u l p h a t e c o n t a i n i n g solution. The m e m b r a n e s a r e also s u i t a b l e for desalinating brackish water and for c o n c e n t r a t i n g o r a n g e Juice.
Patent number: US 5 2 6 2 0 5 4 Date: 16 November 1993 Inventor: J.W. Wheeler Applicant: E I Du Pont de N e m o u r s a n d Co.
Permanently hydrophilic polysulphone membrane The m e m b r a n e s m a d e b y t h i s p r o c e s s r e t a i n their hydrophflicity even after r e p e a t e d sterilization in a c u r r e n t of s t e a m a t 134°C for a total sterilization time of 1 h o u r a n d after r e p e a t e d e x t r a c t i o n with boiling e t h a n o l for a total time of two h o u r s . They a r e t h u s s u i t a b l e for sterile filtration of p h a r m a c e u t i c a l a n d food i n d u s t r i e s solutions, a n d c a n b e sterilized in situ with t h e o t h e r c o m p o n e n t s of the filtration equipment. The s t a r t i n g m e m b r a n e s are m a d e b y c a s t i n g a solution b a s e d on a r o m a t i c p o l y s u l p h o n e s on a s m o o t h fiat surface. The m e m b r a n e is t h e n i m p r e g n a t e d with a n a q u e o u s s o l u t i o n which c o n t a i n s 0.01-2% polyvinylpyrrolldone a n d 0.01-2% of a copolymer of vinylpyrrolidone and a more hydrophobic monomer. The s o l u t i o n also c o n t a i n s 0.5% s o d i u m p e r o x y s u l p h a t e a n d e n o u g h s h o r t - c h a l n alkyl alcohol to p r e v e n t it b e c o m i n g cloudy. The i m p r e g n a t e d m e m b r a n e is h e a t e d for 1-60 m i n u t e s at a
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t e m p e r a t u r e of 70-150°C a n d is cooled to r o o m t e m p e r a t u r e a n d w a s h e d in water.
Patent number: EP 571871 Date: 1 December 1993 Inventors: H.J. Muller, T. Rennet, A. K u c h a r Applicant: Seitz-Fflter-Werke GmbH
Biotechnology separations Biologically active m a t e r i a l s often n e e d to be s u p p l i e d at high p u r i t y in order to avoid the d e l e t e r i o u s effects of impurities. W h e n the r e q u i r e d m a t e r i a l is only one c o m p o n e n t of the r e s u l t s of a f e r m e n t a t i o n p r o c e s s , for example, the t a s k of s e p a r a t i n g one p r o t e i n or p e p t i d e from m a n y o t h e r s with similar p h y s i c a l p r o p e r t i e s is considerable. Gel m e m b r a n e s have b e e n u s e d for s u c h s e p a r a t i o n s b u t are n o t very selective, a n d s h o w a micro-filter effect to large p r o t e i n s (MW 500 000). Most p r i o r - a r t m e m b r a n e s have b e e n b a s e d on a g a r o s e or p o l y a c r y l a m i d e : a g a r o s e h a s little m e c h a n i c a l s t r e n g t h a n d p o l y a c r y l a m i d e is toxic (and the m o n o m e r p r e c u r s o r , acrylamide, is carcinogenic). The specification of the m e m b r a n e - f o r m i n g m a t e r i a l s in this invention is very b r o a d : t h e e s s e n t i a l criteria is t h a t t h e y a r e r e a c t i o n p r o d u c t s between hydroxy group-contalning neutral polymers, a n d diazine or triazine derivatives of a m i n o c a r b o x y l i c or a m i n o s u l p h o n i c acids, or of m o n o - or polyamlnes. The gel m e m b r a n e is a c r o s s - l i n k e d m i x t u r e of anionic a n d cationic reaction products. Natural polymers containing h y d r o x y g r o u p s are a g a r o s e or other p o l y s a c c h a r i d e s , s y n t h e t i c p o l y m e r s are legion b u t i n c l u d e polyvinyl alcohol a n d h y d r o x y a l k y l a c r y l a t e s a n d their c o p o l y m e r s with vinylethylether. Preferred p o l y m e r s are m o s t l y m e t h a c r y l a t e s . The manufacturing methods and p r o d u c t forming t e c h n i q u e s also form p a r t of the p a t e n t .
Patent number: EP 5 7 2 3 5 4 Date: I D e c e m b e r 1993
Inventors: R. Ketraro, C. Linder, M. Nemas, M, Perry ApplicanC Aligena AG
Indirect contact extraction Liquid-liquid e x t r a c t i o n h a s b e e n a n i n d u s t r i a l - s c a l e t e c h n i q u e for generations: an impure aqueous s o l u t i o n is c o n t a c t e d with a n i m m i s c i b l e organic liquid which, either t h r o u g h i t s own p r o p e r t i e s or t h r o u g h a s o l u b l e r e a g e n t d i s s o l v e d in t h e organic liquid, provides a preferential e n v i r o n m e n t for one or m o r e i m p u r i t i e s in t h e a q u e o u s solution. The organic liquid is t h e n removed, a n d is p u r g e d of its cargo b y w a s h i n g w i t h a t h i r d i m m i s c i b l e liquid, u s u a l l y water. This is the c l a s s i c m e t h o d of r e m o v i n g m e t a l ions from c o m p l e x solutions: it is u s e d to e x t r a c t p a r t i c u l a r ions in n u c l e a r w a s t e p r o c e s s i n g p l a n t s . The disadvantages include c o n t a m i n a t i o n of the a q u e o u s s o l u t i o n s b y s m a l l b u t significant a m o u n t s of the organic solvent. There are also p r o c e s s e s in which the a q u e o u s a n d organic p h a s e s are separated by membranes. The inventive s t e p p a t e n t e d h e r e is t h a t t h e i n t e r m e d i a t e organic solvent is r e p l a c e d b y a n aqueous solution which contains an extraction reagent which c a p t u r e s the d e s i r e d ion(s). M e m b r a n e s a r e u s e d to s e p a r a t e the feed solution from the receiver p h a s e a n d from the third, p r o d u c t , solution. The e x t r a c t i o n r e a g e n t s a r e selected a c c o r d i n g to t h e s o l u t e to be e x t r a c t e d , so crown e t h e r s a n d EDTA will be u s e d to recover cations, while a l k y l a m i n e s will be c h o s e n for a n i o n recovery. The e x t r a c t i o n r e a g e n t m o l e c u l a r weight m u s t be large e n o u g h t h a t it is n o t lost through the membranes.
Patent number: WO 9 3 2 3 1 5 0 Date: 25 November 1993 Inventors: A.M. Eyal, A. Banlel. E. Bressler, M.J. C o p l a n Applicant: Y i s s u m R e s e a r c h a n d D e v e l o p m e n t Co, Hebrew University of J e r u s a l e m
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Patents This is a list of r e c e n t l y p u b l i s h e d p a t e n t s covering d e s i g n s a n d i n v e n t i o n s of r e l e v a n c e to s y n t h e t i c m e m b r a n e technology. Where the s a m e device h a s b e e n p a t e n t e d in several c o u n t r i e s , we n o r m a l l y give t h e British p a t e n t n u m b e r . If t h e r e is no UK p a t e n t , we give the n u m b e r of a n E n g l i s h - l a n g u a g e p a t e n t , i f one exists. The p a t e n t s list is c o m p i l e d from i n t e r n a t i o n a l s o u r c e s by BHR G r o u p ' s i n f o r m a t i o n service. The facility c a n also be u s e d to carry out retrospective patent s e a r c h e s - - to t e s t t h e validity, novelty or i n f r i n g e m e n t of existing p a t e n t s or n e w ideas. BHR Group, Cranfleld, Bedford MK43 OAJ, UK, will provide free e s t i m a t e s on r e q u e s t . C o u n t r i e s c a n be identified b y the code in front of the n u m b e r a s follows:
15th a n d E a s t Streets, NW Washington, DC 20231, USA The J a p a n e s e P a t e n t Office 4-3 K a k s u m i g a s e k l 3 - c h o m e C h i y o d a - k u , Tokyo 100, J a p a n
Modifying hollow fibre membranes
G a s p l a s m a t r e a t m e n t to modify the p r o p e r t i e s of m e m b r a n e s is u s u a l l y a p p l i e d to fiat m e m b r a n e s . This invention p e r m i t s hollow fibres to be modified easily a n d with c o n s i s t e n t r e s u l t s a r o u n d the c i r c u m f e r e n c e of the fibre lumen. A b u n c h of fibres, in its h o u s i n g a n d with the e n d s s e c u r e d in the t u b e - p l a t e s , is p l a c e d in a t u b u l a r reactor. The fibres a r e filled with a s u i t a b l e g a s a n d the p r e s s u r e i n s i d e the r e a c t o r is r e d u c e d so t h a t there is a p r e s s u r e difference a c r o s s the AU A u s t r a l i a AT A u s t r i a fibres. BR Brazil BE Belgium An a n t e n n a in the s h a p e of a DD E a s t G e r m a n y CH S w i t z e r l a n d coil with d i a m e t e r larger t h a n the DK D e n m a r k DE West G e r m a n y r e a c t o r is energized a n d p a s s e s EP E u r o p e a n P a t e n t s ES S p a i n along the length of the reactor. In FI F i n l a n d FR F r a n c e GB Britain HU H u n g a r y this w a y the p l a s m a t r e a t m e n t is IR Eire IL Israel equalized t h r o u g h o u t the fibre IT Italy JP Japan b u n d l e . The p r o c e s s is rapid. KP North Korea LI L i e c h t e n s t e i n The c h o s e n m e m b r a n e is NL N e t h e r l a n d s LU L u x e m b o u r g poly(4-methylpentene) a n d the NO Norway RO R o m a n i a g a s is c a r b o n tetrafluoride. US United S t a t e s SE S w e d e n SU Soviet Union WO World P a t e n t Patent number: JP 5317661 (Patent T r e a t y Date: 3 December 1993 Cooperation Inventor: T. A n a z a w a publication) Applicant: D a i n i p p o n I n k a n d Chemical Co. BHR G r o u p does n o t o p e r a t e a d o c u m e n t delivery service for p a t e n t s , b u t full copies of the original p a t e n t d o c u m e n t s c a n be o b t a i n e d from t h e foUowing addresses: The British L i b r a r y P a t e n t E x p r e s s 25 S o u t h a m p t o n B u i l d i n g s London WC2A lAW, UK Fax: 071 323 7230 (The British L i b r a r y will a l s o s u p p l y a llst of UK l i b r a r i e s i n c l u d e d in the P a t e n t I n f o r m a t i o n Network.) US P a t e n t Office Scientific L i b r a r y
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Photographic membrane formation
The top s u r f a c e of t h i s m u l t i l a y e r m e m b r a n e is p r o d u c e d u s i n g a m a s k and a photosensitive lacquer, which forms a t h i n layer on top of a s p u t t e r e d or c h e m i c a l l y d e p o s i t e d inorganic m e m b r a n e . Both are s u p p o r t e d by a m a c r o p o r o u s m a t e r i a l s u c h as alpha-alumina.
The s p u t t e r e d m e m b r a n e is a c e r a m i c s u c h a s silica, silicon nitride, silicon carbide, or ztrconia. Metals c a n also be used: a m o n g those listed are t i t a n i u m , gold, c h r o m i u m a n d a l u m i n i u m . The s p u t t e r i n g p r o c e s s leaves a m e m b r a n e layer with pore sizes in the r a n g e 0.01-10 microns, a n d a typical t h i c k n e s s of 2-5 microns. A p h o t o s e n s i t i v e l a c q u e r is t h e n c o a t e d onto the s u r f a c e of the s p u t t e r e d m e m b r a n e a n d a m a s k with r e g u l a r l y - s p a c e d holes is u s e d to cover the surface. The d i a m e t e r of the holes is 3 microns. The l a c q u e r is developed a n d the e x p o s e d m a t e r i a l is r e m o v e d u s i n g standard lithographic methods. Next the holes in the l a c q u e r a r e d e e p e n e d b y e t c h i n g with t e t r a m e t h y l a m m o n i u m hydride, a n d finally the l a c q u e r is removed to leave a n inorganic m e m b r a n e with a regular, defined pore s t r u c t u r e at its o u t e r surface.
Patent number: WO 9323154 Date: 25 November 1993 Inventor and applicant: C.J.M. v a n RiJn
Opening membrane pores In t h i s p r o c e s s a m e m b r a n e which w a s originally s u i t a b l e for reverse o s m o s i s a p p l i c a t i o n s c a n be modified so t h a t it c a n t h e n i n s t e a d be u s e d for nanoflltration. The i n c r e a s e in pore size n e c e s s a r y to do this is o b t a i n e d by c o n t a c t i n g the m e m b r a n e (an a s y m m e t r i c hollow fibre p o l y a m i d e material) with a solution of a t r a n s i t i o n m e t a l salt, typically m a n g a n e s e . The t r a n s i t i o n m e t a l is in a low o x i d a t i o n state. The wet m e m b r a n e is t h e n w a s h e d with a s o l u t i o n of s o d i u m or p o t a s s i u m p e r m a n g a n a t e . The t r a n s i t i o n m e t a l is oxidized by t h e p e r m a n g a n a t e a n d p r e c i p i t a t e s in the p o r e s a s a m e t a l oxide, e.g. m a n g a n e s e dioxide. In the final s t e p t h e m e t a l oxide is dissolved b y r e a c t i o n with
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Patents a solution containing sodium nitrite, p o t a s s i u m iodide, s o d i u m bisulphite and hydrogen peroxide. The s e q u e n c e of s t e p s c a n be r e p e a t e d several t i m e s until the average p o r e size h a s b e e n e ~ l a r g e d to t h e d e s i r e d extent. The p r o c e s s h a s b e e n u s e d to produce nanoflltration m e m b r a n e s which will p a s s s o d i u m chloride a n d s o d i u m s u l p h a t e , w h i c h is a p r o p e r t y useful in the s e p a r a t i o n of a dye from a s o d i u m s u l p h a t e c o n t a i n i n g solution. The m e m b r a n e s a r e also s u i t a b l e for desalinating brackish water and for c o n c e n t r a t i n g o r a n g e Juice.
Patent number: US 5 2 6 2 0 5 4 Date: 16 November 1993 Inventor: J.W. Wheeler Applicant: E I Du Pont de N e m o u r s a n d Co.
Permanently hydrophilic polysulphone membrane The m e m b r a n e s m a d e b y t h i s p r o c e s s r e t a i n their hydrophflicity even after r e p e a t e d sterilization in a c u r r e n t of s t e a m a t 134°C for a total sterilization time of 1 h o u r a n d after r e p e a t e d e x t r a c t i o n with boiling e t h a n o l for a total time of two h o u r s . They a r e t h u s s u i t a b l e for sterile filtration of p h a r m a c e u t i c a l a n d food i n d u s t r i e s solutions, a n d c a n b e sterilized in situ with t h e o t h e r c o m p o n e n t s of the filtration equipment. The s t a r t i n g m e m b r a n e s are m a d e b y c a s t i n g a solution b a s e d on a r o m a t i c p o l y s u l p h o n e s on a s m o o t h fiat surface. The m e m b r a n e is t h e n i m p r e g n a t e d with a n a q u e o u s s o l u t i o n which c o n t a i n s 0.01-2% polyvinylpyrrolldone a n d 0.01-2% of a copolymer of vinylpyrrolidone and a more hydrophobic monomer. The s o l u t i o n also c o n t a i n s 0.5% s o d i u m p e r o x y s u l p h a t e a n d e n o u g h s h o r t - c h a l n alkyl alcohol to p r e v e n t it b e c o m i n g cloudy. The i m p r e g n a t e d m e m b r a n e is h e a t e d for 1-60 m i n u t e s at a
M e m b r a n e T e c h n o l o g y No. 51
t e m p e r a t u r e of 70-150°C a n d is cooled to r o o m t e m p e r a t u r e a n d w a s h e d in water.
Patent number: EP 571871 Date: 1 December 1993 Inventors: H.J. Muller, T. Rennet, A. K u c h a r Applicant: Seitz-Fflter-Werke GmbH
Biotechnology separations Biologically active m a t e r i a l s often n e e d to be s u p p l i e d at high p u r i t y in order to avoid the d e l e t e r i o u s effects of impurities. W h e n the r e q u i r e d m a t e r i a l is only one c o m p o n e n t of the r e s u l t s of a f e r m e n t a t i o n p r o c e s s , for example, the t a s k of s e p a r a t i n g one p r o t e i n or p e p t i d e from m a n y o t h e r s with similar p h y s i c a l p r o p e r t i e s is considerable. Gel m e m b r a n e s have b e e n u s e d for s u c h s e p a r a t i o n s b u t are n o t very selective, a n d s h o w a micro-filter effect to large p r o t e i n s (MW 500 000). Most p r i o r - a r t m e m b r a n e s have b e e n b a s e d on a g a r o s e or p o l y a c r y l a m i d e : a g a r o s e h a s little m e c h a n i c a l s t r e n g t h a n d p o l y a c r y l a m i d e is toxic (and the m o n o m e r p r e c u r s o r , acrylamide, is carcinogenic). The specification of the m e m b r a n e - f o r m i n g m a t e r i a l s in this invention is very b r o a d : t h e e s s e n t i a l criteria is t h a t t h e y a r e r e a c t i o n p r o d u c t s between hydroxy group-contalning neutral polymers, a n d diazine or triazine derivatives of a m i n o c a r b o x y l i c or a m i n o s u l p h o n i c acids, or of m o n o - or polyamlnes. The gel m e m b r a n e is a c r o s s - l i n k e d m i x t u r e of anionic a n d cationic reaction products. Natural polymers containing h y d r o x y g r o u p s are a g a r o s e or other p o l y s a c c h a r i d e s , s y n t h e t i c p o l y m e r s are legion b u t i n c l u d e polyvinyl alcohol a n d h y d r o x y a l k y l a c r y l a t e s a n d their c o p o l y m e r s with vinylethylether. Preferred p o l y m e r s are m o s t l y m e t h a c r y l a t e s . The manufacturing methods and p r o d u c t forming t e c h n i q u e s also form p a r t of the p a t e n t .
Patent number: EP 5 7 2 3 5 4 Date: I D e c e m b e r 1993
Inventors: R. Ketraro, C. Linder, M. Nemas, M, Perry ApplicanC Aligena AG
Indirect contact extraction Liquid-liquid e x t r a c t i o n h a s b e e n a n i n d u s t r i a l - s c a l e t e c h n i q u e for generations: an impure aqueous s o l u t i o n is c o n t a c t e d with a n i m m i s c i b l e organic liquid which, either t h r o u g h i t s own p r o p e r t i e s or t h r o u g h a s o l u b l e r e a g e n t d i s s o l v e d in t h e organic liquid, provides a preferential e n v i r o n m e n t for one or m o r e i m p u r i t i e s in t h e a q u e o u s solution. The organic liquid is t h e n removed, a n d is p u r g e d of its cargo b y w a s h i n g w i t h a t h i r d i m m i s c i b l e liquid, u s u a l l y water. This is the c l a s s i c m e t h o d of r e m o v i n g m e t a l ions from c o m p l e x solutions: it is u s e d to e x t r a c t p a r t i c u l a r ions in n u c l e a r w a s t e p r o c e s s i n g p l a n t s . The disadvantages include c o n t a m i n a t i o n of the a q u e o u s s o l u t i o n s b y s m a l l b u t significant a m o u n t s of the organic solvent. There are also p r o c e s s e s in which the a q u e o u s a n d organic p h a s e s are separated by membranes. The inventive s t e p p a t e n t e d h e r e is t h a t t h e i n t e r m e d i a t e organic solvent is r e p l a c e d b y a n aqueous solution which contains an extraction reagent which c a p t u r e s the d e s i r e d ion(s). M e m b r a n e s a r e u s e d to s e p a r a t e the feed solution from the receiver p h a s e a n d from the third, p r o d u c t , solution. The e x t r a c t i o n r e a g e n t s a r e selected a c c o r d i n g to t h e s o l u t e to be e x t r a c t e d , so crown e t h e r s a n d EDTA will be u s e d to recover cations, while a l k y l a m i n e s will be c h o s e n for a n i o n recovery. The e x t r a c t i o n r e a g e n t m o l e c u l a r weight m u s t be large e n o u g h t h a t it is n o t lost through the membranes.
Patent number: WO 9 3 2 3 1 5 0 Date: 25 November 1993 Inventors: A.M. Eyal, A. Banlel. E. Bressler, M.J. C o p l a n Applicant: Y i s s u m R e s e a r c h a n d D e v e l o p m e n t Co, Hebrew University of J e r u s a l e m
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